1. Field of the Invention
The present invention generally relates to fluid coupling devices; and more particularly to hydrokinetic torque converters not having thrust bearings between a stator and impeller and turbine shells, and a method for making the same.
2. Background of the Invention
Typically, a hydrokinetic torque converter includes an impeller, a turbine, a stator (or reactor) fixed to a casing of the torque converter, and a one-way clutch for restricting rotational direction of the stator to one direction. The turbine is integrally or operatively connected with a hub linked in rotation to a driven shaft, which is itself linked to an input shaft of a transmission of a vehicle. The casing of the torque converter generally includes a front cover and an impeller shell which together define a fluid filled chamber. Impeller blades are fixed to the impeller shell within the fluid filled chamber to define the impeller wheel. The turbine and the stator are also disposed within the chamber, with both the turbine and the stator being relatively rotatable with respect to the front cover and the impeller shell. The turbine includes a turbine shell with a plurality of turbine blades fixed to one side of the turbine shell facing the impeller blades of the impeller.
The turbine works together with the impeller, which is linked in rotation to the casing that is linked in rotation to a driving shaft driven by an internal combustion engine. The stator is interposed axially between the turbine and the impeller, and is mounted so as to rotate on the driven shaft with the interposition of the one-way clutch.
Current hydrokinetic torque converters are provided with thrust bearings on axially opposite sides of the one-way clutch. One of the thrust roller bearings is disposed between the impeller and the one-way clutch (or a stator hub), and another thrust roller bearing is disposed between the turbine and the one-way clutch. The thrust roller bearings are provided to limit the relative movement between the impeller, the stator and the turbine in the axial direction. In other words, the thrust roller bearings maintain the position of the stator with respect to the impeller and the turbine for relative rotation with respect to each other. The thrust roller bearings are costly and take up a significant amount of axial space within the torque convertor. Therefore, reducing the size of the thrust bearings or eliminating the thrust bearings altogether, would allow the cost and weight of the torque convertor to be reduced and to reduce an axial length thereof.
Current hydrokinetic torque converters and methods for assembling thereof are quite complex, cumbersome and expensive. Therefore, while conventional hydrokinetic torque converters, including but not limited to that discussed above, have proven to be acceptable for vehicular driveline applications and conditions, improvements that may enhance their performance and cost are possible.